Membrane switches are well known for providing electrical switching functions in a reliable, compact package. Membrane switches typically have a flexible plastic membrane layer normally separated from a substrate by a nonconductive spacer. Openings in the spacer permit a user to push the membrane through the spacer, bringing facing electrical contacts on the internal surfaces of the membrane and substrate into contact with one another, thereby closing a switch. The natural resilience of the membrane returns the membrane to its spaced position upon removal of the actuating force.
While this basic membrane switch construction has many advantages, it does not provide some features desirable in certain applications. For example, in some instances switch users are so accustomed to manipulating a particular type of mechanical actuator that they become confused by and consequently resistant to a membrane switch. The membrane switch is often a flat panel with graphical elements indicating where to press but having no protruding actuating member. Although membrane switches provide perfectly adequate electrical switching, manufacturers have found that users expecting to find a rotary switch or a slide switch or a pushbutton switch for a certain function don't take kindly to having the familiar switch replaced with a flat panel membrane switch. This is especially true with consumer products. Also, in automotive applications it can be important to provide a rotary or slide switch that a driver can find and manipulate with one hand while not diverting his or her attention from the road.
Another ongoing problem in membrane switches has been providing feedback to a user of switch actuation. Since the membrane travel to closure is very small most users cannot tell when they have actuated a switch unless there is something to indicate to them that closure has occurred. Aural feedback is common but not always desirable. Tactile feedback has been provided by clicker domes built into the membrane. In full travel keyboards feedback has been provided by a plastic actuator mounted above the membrane switch panel. Such actuators are usually complicated little devices which makes them relatively expensive.